Method for forming lubricant layer on surface of glass and method for manufacturing glass using the same

ABSTRACT

A method for forming a lubricant layer on the surface of a glass and a method for manufacturing a glass using the same prevents scratches from occurring at the surface of a glass and decreases corrosion of glass manufacturing equipment. The method for manufacturing a glass includes forming a glass, supplying SO 2  gas and a SO 2  gas oxidation catalyst to the glass under an oxidation environment to form a lubricant layer at the lower surface of the glass, and annealing the glass.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of International Application No.PCT/KR2012/001273 filed on Feb. 20, 2012, which claims priority under 35USC 119(a) to Korean Patent Application No. 10-2011-0015039 filed onFeb. 21, 2011 and Korean Patent Application No. 10-2012-0017126 filed onFeb. 20, 2012 in the Republic of Korea, the entire contents of which areincorporated herein by reference.

BACKGROUND OF THE DISCLOSURE

1. Field of the Disclosure

The present disclosure relates to a glass manufacturing technique, andmore particularly, to a method for forming a lubricant layer on thesurface of a glass and a method for manufacturing a glass using thesame, which may prevent scratches from occurring at the surface of aglass and decrease corrosion of glass manufacturing equipment.

2. Description of the Related Art

Many kinds of flat glasses are being used in various fields like windowpanes, window screens of vehicles and mirrors. Such a flat glass may bemanufactured in various ways. Among them, a representative method is aproduction method using a float method. For example, thin glass planesor glass films for TFT displays are frequently manufactured by the floatmethod. The glass manufactured by the float method is called a floatglass.

FIG. 1 is a schematic diagram showing a system for manufacturing a floatglass.

As shown in FIG. 1, a float glass is generally formed by using a floatbath 10 where a molten metal M such as molten tin or molten tin alloy isstored and flows. At this time, a molten glass having a lower viscositythan the molten metal M and lighter than the molten metal M by about ⅔is successively supplied into the float bath 10 through an inlet of thefloat bath 10. The molten glass moves to the downstream of the floatbath 10 while floating and spreading on the molten metal M. In thisprocess, the molten glass nearly reaches an equivalent thicknessaccording to its surface tension and gravity to form a glass strip orribbon which is solidified to some extent.

In addition, the molten glass ribbon formed as above is transferred fromthe float bath 10 to an annealing furnace 20 and experiences anannealing process. In the annealing process, the glass is transferredfrom an inlet to an outlet of the annealing furnace 20 by transfer meanssuch as a roller 30 or a belt. In addition, after the annealing process,the glass may also be carried by the transfer means such as the roller30.

While the glass is transferred in the annealing process or after theannealing process, the lower surface of the glass may come into contactwith the transfer means such as the roller 30. At this time, due to thetransfer means such as the roller 30, flows, cracks or scratches mayoccur at the lower surface of the glass. Particularly, if the aboveequipment is used continuously, impurities or glass fractures may beattached to the transfer means such as the roller 30. In this case,scratches may occur more easily at the lower surface of the glass.

If scratches occur at the lower surface of the glass during a glasstransferring process using the roller 30 or the lime, the quality andyield of glass greatly deteriorate. Therefore, efforts are being made toprevent scratches from occurring at the lower surface of a glass duringthe glass transferring process, particularly in the annealing furnace20, or during a process of transferring a glass after the annealingprocess.

Among them, a representative technique is to supply SO₂ gas to the lowersurface of a glass at an initial stage of the glass annealing process orbefore the glass annealing process. If the SO₂ gas is sprayed to thelower surface of a glass as described above, the SO₂ gas reacts withalkali components of the glass, particularly sodium components, to formsulphate such as Na₂SO₄. In addition, the formed sulphate serves as alubricant layer since its film strength is higher than that of a glass,thereby preventing scratches from occurring at the lower surface of theglass by the transfer means such as the roller 30 and improving thescratch resistance of the glass.

However, in case of a non-alkali glass substantially not containing analkali component such as sodium, like a glass for LCD, even though SO₂gas is supplied, a sulphate lubricant layer is not easily formed by analkali metal such as Na₂SO₄. The SO₂ gas should react with componentssuch as alkali earth metal like calcium in the glass to form a sulphatelubricant layer such as CaSO₄, but the SO₂ gas does not easily reactwith alkali earth metals or the like in comparison to alkali metals suchas sodium. Therefore, in order to form a lubricant layer such as CaSO₄,an excessive amount of SO₂ gas should be used. However, if a lot of SO₂gas is used, the production cost may increase accordingly. In addition,the toxicity of the SO₂ gas may act as a source of environmentalpollution and cause serious harm to workers health.

Moreover, since manufacturing equipment or instruments such as theannealing furnace 20 may be easily corroded due to SO₂ gas, theproductivity and process efficiency when manufacturing glasses may beadversely affected. For this reason, the SO₂ gas should be used aslittle as possible. However, in the conventional technique, an excessiveamount of SO₂ gas should be inevitably used to form a lubricant layerfor preventing scratches from occurring at the lower surface of a glass.

SUMMARY OF THE DISCLOSURE Technical Problem

The present disclosure is designed to solve the problems of the priorart, and therefore it is an object of the present disclosure to providean apparatus for forming a lubricant layer on the surface of a glass,which may use a small amount of SO₂ gas and effectively preventscratches from occurring at the surface of the glass; and a method formanufacturing a glass using the same.

Other objects and advantages of the present disclosure will beunderstood by the following description and become more apparent fromthe embodiments of the present disclosure, which are set forth herein.It will also be apparent that objects and advantages of the presentdisclosure can be embodied easily by the means defined in claims andcombinations thereof.

Technical Solution

In order to accomplish the above object, the present disclosure providesa method for manufacturing a glass, which includes forming a glass;supplying SO₂ gas and a SO₂ gas oxidation catalyst to the glass under anoxidation environment to form a lubricant layer at the lower surface ofthe glass; and annealing the glass.

Preferably, the SO₂ gas is oxidized into SO₃ gas under the oxidationenvironment.

Also preferably, the SO₂ gas oxidation catalyst includes V₂O₅.

Also preferably, the lubricant layer formed in the lubricant layerforming process includes CaSO₄.

In addition, in order to accomplish the above object, the presentdisclosure provides a glass, which is manufactured by the above methodfor manufacturing a glass.

In addition, in order to accomplish the above object, the presentdisclosure provides a method for forming a lubricant layer on thesurface of a glass by using SO₂ gas, wherein the SO₂ gas is supplied tothe glass together with a SO₂ gas oxidation catalyst under an oxidationenvironment.

Preferably, the SO₂ gas is oxidized into SO₃ gas under the oxidationenvironment.

Also preferably, the SO₂ gas oxidation catalyst includes V₂O₅.

Also preferably, the lubricant layer includes CaSO₄.

In addition, in order to accomplish the above object, the presentdisclosure provides an apparatus for manufacturing a glass, whichincludes: a glass forming unit for forming a glass; a SO₂ supply unitfor supplying SO₂ gas to the formed glass; an O₂ supply unit forsupplying O₂ gas to the formed glass; and a catalyst supply unit forsupplying a SO₂ gas oxidation catalyst with respect to the SO₂ gassupplied to the glass.

Advantageous Effects

According to the present disclosure, since a lubricant layer is easilyformed at the surface of a glass, particularly the lower surface of theglass which directly contacts a roller or the like, the scratchresistance of the glass may be improved. Therefore, when the glass istransferred by the transfer means such as a roller and a belt during amanufacturing process such as a glass annealing process, it is possibleto effectively prevent flaws, cracks or scratches from occurring at thelower surface of the glass. Therefore, a defect rate may be loweredduring the glass manufacturing process and a high-quality glass may beobtained. In addition, since scratches at the glass decrease, time andcosts required for polishing the glass may be reduced.

Further, according to the present disclosure, a sulphate lubricant layermay be sufficiently formed at the surface of a glass by using a smallamount of SO₂ gas. Therefore, it is possible to suppress SO₂ gas withstrong toxicity causing environmental pollution and bringing harmfulworking conditions to a worker. In addition, the SO₂ gas may be moresimply purchased and treated at low costs. Moreover, it is possible tosuppress that glass manufacturing equipment or instruments such as anannealing furnace from being corroded by the SO₂ gas, which may extendthe life span of the glass manufacturing equipment or instruments.

Particularly, in case of a non-alkali glass substantially not containingan alkali metal such as sodium, like a glass for LCD, a sulphatelubricant layer may be sufficiently formed by using a relatively smallamount of SO₂ gas.

In addition, since the time required for forming the sulphate lubricantlayer is shortened, the time required for the entire glass manufacturingprocess may be shortened and the production cost may be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and aspects of the present disclosure will become apparentfrom the following descriptions of the embodiments with reference to theaccompanying drawings in which:

FIG. 1 is a schematic diagram showing a system for manufacturing a floatglass;

FIG. 2 is a flowchart for schematically illustrating a method formanufacturing a glass according to an embodiment of the presentdisclosure;

FIG. 3 is a schematic diagram showing an example where SO₂ gas and SO₂gas oxidation catalyst are supplied to a glass in an annealing furnacein order to form a lubricant layer at the lower surface of the glassaccording to an embodiment of the present disclosure;

FIG. 4 is a schematic diagram showing a configuration for causing anoxidation reaction of SO₂ gas at the surface of a glass plate bysupplying SO₂ gas and SO₂ gas oxidation catalyst together to the glassplate according to an embodiment of the present disclosure;

FIG. 5 is a schematic diagram showing a configuration for measuring thescratch resistance of a glass plate in a Taber manner;

FIG. 6 is a graph showing measurement results of Ca and S contents ateach depth of the glass plate according to an example of the presentdisclosure and a comparative example;

FIG. 7 is a table which expresses the graph of FIG. 6 with numerals; and

FIG. 8 is a block diagram schematically showing a functionalconfiguration of an apparatus for manufacturing a glass according to anembodiment of the present disclosure.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, preferred embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings. Priorto the description, it should be understood that the terms used in thespecification and the appended claims should not be construed as limitedto general and dictionary meanings, but interpreted based on themeanings and concepts corresponding to technical aspects of the presentdisclosure on the basis of the principle that the inventor is allowed todefine terms appropriately for the best explanation.

Therefore, the description proposed herein is just a preferable examplefor the purpose of illustrations only, not intended to limit the scopeof the disclosure, so it should be understood that other equivalents andmodifications could be made thereto without departing from the spiritand scope of the disclosure.

FIG. 2 is a flowchart for schematically illustrating a method formanufacturing a glass according to an embodiment of the presentdisclosure.

Referring to FIG. 2, a glass is firstly formed by using a molten glassto make a glass according to the present disclosure (S110). The glassforming process S110 may be performed in various ways, and the presentdisclosure is not limited to a specific glass forming manner.

Preferably, the glass forming process S110 may be performed by means ofa float method. In other words, as shown in FIG. 1, a molten glass issupplied to a float bath 10 storing a molten metal M and floated andspread on the metal M to form a glass. At this time, the thickness of aglass ribbon may be changed by adjusting the amount of glass put throughan inlet of the float bath 10 or by controlling forming means such astop rollers 30 installed in the float bath 10. The glass forming processusing such a float method is well known in the art and is not describedin detail here. The float glass manufacturing method includes cyclicsuccessive processes and may operate constantly without a cessation,which allows flat glasses to be manufactured for several years without apause. This is very suitable for glass forming. In addition, variousglass forming methods well known in the art at the filing of the presentdisclosure may be adopted in the glass forming process S110 of thepresent disclosure.

If a glass is formed from a molten glass as described above, the glassis annealed (S130). The method for manufacturing a glass according tothe present disclosure performs forming a lubricant layer at the lowersurface of the glass (S120) before performing the glass annealingprocess S130. Here, ‘before performing the glass annealing process S130’means the moment before the glass annealing process S130 is entirelycompleted, which includes the moment before the glass annealing processS130 is initiated as well as the moment the glass annealing process S130is proceeding but not yet completed. For example, the lubricant layerforming process S120 may be performed at an early stage of the glassannealing process S130. In the lubricant layer forming process S120, themethod for manufacturing a glass according to the present disclosuresupplies SO₂ gas and SO₂ gas oxidation catalyst to the glass under anoxidation environment in order to form a lubricant layer at the lowersurface of the glass.

The SO₂ gas reacts with some components of the glass to generatesulphate so that a lubricant layer may be formed at the lower surface ofthe glass by the sulphate. Particularly, in case of a non-alkali glass,the SO₂ gas supplied in the lubricant layer forming process S120 mayreact with a component such as calcium contained in the glass to form asulphate lubricant layer.

SO₂(g)+½×O₂(g)→SO₃(g)  Formula 1

SO₃(g)+CaO(s)→CaSO₄(s)  Formula 2

In other words, the SO₂ gas, supplied under an oxidation environmentwhere oxygen is present, reacts with oxygen and is oxidized into SO₃gas, as shown in Formula 1. In addition, the SO₃ gas generated as abovereacts with calcium oxide contained in the glass to form CaSO₄ so that alubricant layer is formed at the surface of the glass.

Even though Formula 2 shows only the process where SO₂ gas reacts withCaO in the glass to form a CaSO₄ lubricant layer, the SO₂ gas may alsoreact with another component of the glass to form a lubricant layer byanother kind of sulphate. For example, the SO₂ gas may react with MgO orCr₂O₃ of the glass to form a sulphate lubricant layer such as MgSO₄ andCr₂ (SO₄)₃. Since the SO₂ gas supplied to the glass as described abovereacts with a certain component of the glass and forms a lubricant layerat the surface by sulphate, it is possible to prevent flaws, cracks orscratches from occurring at the surface of the glass.

Particularly, the method for manufacturing a glass according to thepresent disclosure supplies the SO₂ gas oxidation catalyst together withthe SO₂ gas. Here, the SO₂ gas oxidation catalyst represents a catalystwhich may promote a chemical reaction of Formula 1 where SO₂ gas isoxidized into SO₃ gas.

Preferably, the SO₂ gas oxidation catalyst may include V₂O₅. In a casewhere V₂O₅, namely vanadium pentoxide, is added together with SO₂ gas,the oxidation reaction of the SO₂ gas into SO₃ gas is promoted. Inaddition, as SO₂ gas is oxidized into SO₃ gas more and more, thereaction for forming CaSO₄ by the SO₃ gas as in Formula 2 may beactively performed. Therefore, the lubricant layer of CaSO₄ may besufficiently formed by using just a small amount of SO₂ gas. Since V₂O₅has good resistance against catalyst inactivation of SO₂ gas catalyst,V₂O₅ is preferred as a SO₂ gas oxidation catalyst in the presentdisclosure.

When V₂O₅ is supplied as a SO₂ gas oxidation catalyst together with SO₂gas, V₂O₅ may be supplied in various states and forms. For example, V₂O₅may be supplied in the form of powder. In a case where V₂O₅ is suppliedin the form of powder, the reaction area increases and the oxidationreaction of the SO₂ gas in Formula 1 may be performed more actively.However, the present disclosure is not limited to a specific form orstate of V₂O₅. For example, V₂O₅ may be heated over a melting point andthen sprayed.

In addition, various catalysts may be used as the SO₂ gas oxidationcatalyst in addition to V₂O₅. For example, Fe₂O₃, CuO, TiO₂, Cr₂O₃,SiO₂, CaO, Al₂O₃ or WO₃ may be used as the SO₂ gas oxidation catalyst,and at least two of them may be combined and used. As described above,the SO₂ gas oxidation catalyst is not limited to a specific kind ofmaterial if it can promote oxidation of SO₂ gas into SO₃ gas. Inaddition, the SO₂ gas oxidation catalyst may be used together withanother material which enhances activation of the catalyst. For example,V₂O₅ may be used together with K₂O, K₂SO₄, K₂S₂O₇ or the like, whichenhances the catalyst activation of V₂O₅.

As described above, according to the present disclosure, since the SO₂gas oxidation catalyst is supplied together with the SO₂ gas, the SO₂gas is actively oxidized and so a lubricant layer is sufficiently formedby sulphate. Particularly, in case of a non-alkali glass substantiallynot containing alkali ions such as sodium, a lubricant layer is noteasily formed in comparison to an alkali glass. However, according tothe present disclosure, since the SO₂ gas oxidation catalyst may promotethe oxidation reaction of the SO₂ gas as in Formula 1, in a non-alkaliglass, a lubricant layer may be rapidly and sufficiently formed by meansof sulphate by using a small amount of SO₂ gas.

However, even though the above embodiments have been illustrated basedon the case where the present disclosure is applied to a non-alkaliglass, it does not mean that the present disclosure must be applied to anon-alkali glass. In other words, the present disclosure may also beapplied to an alkali glass, and in case of an alkali glass, theformation of alkali metal sulphate such as Na₂SO₄ may be furtherpromoted. Therefore, in this case, a lubricant layer may also besufficiently formed by using a small amount of SO₂ gas.

Meanwhile, in the lubricant layer forming process S120, the SO₂ gas andthe SO₂ gas oxidation catalyst are preferably supplied in the range of±100° C. from a transition temperature of the glass. The reactionbetween SO₂ gas and a glass is actively performed within 100° C. belowor above the transition temperature of the glass. For example, since aglass for LCD has a transition temperature of about 750° C., the SO₂ gasand the SO₂ gas oxidation catalyst may be supplied under a temperatureenvironment of about 650 to 850° C.

In addition, under the oxidation environment where SO₂ gas may beoxidized, moisture or air may be further supplied together with oxygen.In other words, the oxygen used for oxidizing SO₂ gas may be supplied invarious ways so that the oxidation of SO₂ gas may be activated.

The glass annealing process S130 may be performed by using an annealingfurnace 20, and the SO₂ gas and the SO₂ gas oxidation catalyst may besupplied in the annealing furnace 20.

FIG. 3 is a schematic diagram showing an example where SO₂ gas and SO₂gas oxidation catalyst are supplied to a glass in the annealing furnace20 in order to form a lubricant layer at the lower surface of the glassaccording to an embodiment of the present disclosure.

Referring to FIG. 3, the glass formed in the forming process isintroduced though an inlet 21 of the annealing furnace. At this time,the temperature of the inlet 21 of the annealing furnace may be about700 to 800° C. In addition, the glass introduced into the annealingfurnace 20 as described above is annealed while being transferred towardan outlet 22 of the annealing furnace of about 200 to 300° C. by atleast one roller 30 provided at the annealing furnace 20.

Particularly, according to the embodiment of FIG. 3, V₂O₅ serving as theSO₂ gas oxidation catalyst is supplied at the inlet 21 of the annealingfurnace together with SO₂ gas and O₂ gas. Therefore, V₂O₅ promotes theoxidation reaction of SO₂ gas into SO₃ gas, and the SO₃ gas may promotethe formation of sulphate at the lower surface of the glass. Therefore,according to this embodiment, since the lubricant layer is sufficientlyformed at the lower surface of the glass by sulphate, even though thelower surface of the glass comes into contact with the roller 30 locatedin the annealing furnace 20 or the roller 30 provided after theannealing furnace 20, the sufficiently formed lubricant layer maysuppress the formation of scratches at the lower surface of the glass.

Meanwhile, even though the embodiment of FIG. 3 has been illustrated asthe SO₂ gas and the SO₂ gas oxidation catalyst are supplied near theinlet 21 of the annealing furnace, namely at an early stage of theannealing process, it is just an example, and the SO₂ gas and the SO₂gas oxidation catalyst may be supplied in various forms and ways. Forexample, the SO₂ gas and the SO₂ gas oxidation catalyst may be suppliedbefore the glass is introduced to a middle portion of the annealingfurnace 20 or to the inside of the annealing furnace 20.

In addition, even though the embodiment of FIG. 3 has been illustratedas O₂ gas is directly supplied to form an oxidation environment of theSO₂ gas, it is also possible to supply air containing O₂ gas.

The glass according to the present disclosure is a glass preparedaccording to the above glass manufacturing method.

Meanwhile, even though the above embodiment illustrates a lubricantlayer forming at the lower surface of a glass in order to preventscratches from occurring at the lower surface while the glass is beingtransferred by transfer means such as the roller 30 during or after theglass annealing process, the lubricant layer may also be formed atvarious processes of the glass manufacturing method other than the glassannealing process. In other words, if cracks or scratches may occur atthe surface of a glass, SO₂ gas and SO₂ gas oxidation catalyst may besupplied at any process, without being limited to the time before orafter the glass annealing process, to promote the formation of asulphate lubricant layer at the surface of the glass.

Hereinafter, the present disclosure will be described in more detailbased on examples and comparative examples. The embodiments of thepresent disclosure, however, may take several other forms, and the scopeof the present disclosure should not be construed as being limited tothe following examples. The embodiments of the present disclosure areprovided to more fully explain the present disclosure to those havingordinary knowledge in the art to which the present disclosure pertains.

First, the examples and the comparative examples will be compared tolook into the effect of promoting the formation of a sulphate lubricantlayer at the surface of a glass and preventing scratches from occurring,in a case where a SO₂ gas oxidation catalyst is supplied together withSO₂ gas to form a lubricant layer on at least one surface of the glassas in the present disclosure.

Examples 1 to 3

FIG. 4 is a schematic diagram showing a device for supplying SO₂ gas andan SO₂ gas oxidation catalyst to a glass plate to cause an oxidationreaction of the SO₂ gas at the surface of the glass plate according toan embodiment of the present disclosure.

As Examples 1 to 3 according to the present disclosure, as shown in FIG.4, a glass plate for LCD with a size of 15×15 mm was prepared and sealedwith an O-ring. After that, the glass plate was put into a quartz tubefurnace 40 of 650° C. (Example 1), 700° C. (Example 2) and 750° C.(Example 3), and SO₂ gas and O₂ gas were supplied thereto to make anenvironment of SO₂ 5%, O₂ 10%. In addition, V₂O₅ powder was placed onthe supply path of the SO₂ gas and the O₂ gas so that the V₂O₅ powderwas supplied to the glass plate as a SO₂ gas oxidation catalyst. Inaddition, this state was maintained for 60 minutes so that the reactionsof Formulas 1 and 2 occur in the tube furnace 40.

And then, the tube furnace 40 of each example was sufficiently cooledand all reaction gases were exhausted out of the tube furnace 40 byusing nitrogen gas.

After that, the IC (Ion Chromatography) analysis was performed to theglass plates of Examples 1 to 3, respectively, and the number ofscratches was measured by using the Taber manner. The analysis resultsare shown in Table 1 below.

Here, the IC analysis is an analysis method for comparing the degree ofCaSO₄ formed at the surface of the glass plate as a lubricant layer. Forthe IC analysis, each glass plate was put into 10 mg DI water andmaintained at 60° C. for 10 minutes so that CaSO₄ at the surface of theglass plate is dissolved in the DI water, and the IC analysis wasperformed to the solution. At this time, the dissolution of CaSO₄ waschecked by performing an ESCA analysis before or after the IC analysis.

In addition, the measurement of the number of scratches using the Tabermanner is an analysis method for checking scratch resistance at thesurface of the glass plate. The number of scratches of each glass platewas measured according to the method shown in FIG. 5.

FIG. 5 is a schematic diagram showing a configuration for measuring thescratch resistance of a glass plate in a Taber manner.

As shown in FIG. 5, the glass plates of Examples 1 to 3 were placed on aplate and rotated. At this time, two abrading wheels 50 rotate inopposite directions at the upper portion of the glass plate to causescratches at the glass plate. Here, the abrading wheel 50 employs a 500g wheel and the number of rotation was set to 10. After that, each glassplate was washed, and then the number of scratches occurring withininternal 12×12 mm of each glass plate was measured by using an opticalmicroscope.

Comparative Examples 1 to 6

As Comparative Examples 1 to 3 to be compared with Examples 1 to 3, aglass plate for LCD with a size of 15×15 mm was sealed with an O-ringand then put into a tube furnace 40 of 650° C. (Comparative Example 1),700° C. (Comparative Example 2) and 750° C. (Comparative Example 3), andSO₂ gas and O₂ gas were supplied thereto to make an environment of SO₂5%, O₂ 10%, similar to Examples 1 to 3. However, V₂O₅ powder was notsupplied, different from Examples 1 to 3. In addition, this state wasmaintained for 60 minutes so that the reactions of Formulas 1 and 2occur. After the glass plates of Comparative Examples 1 to 3 werereacted in the tube furnace 40 of each condition, the tube furnace 40was cooled and all reaction gases were exhausted out of the tube furnace40 by using nitrogen gas.

In addition, as Comparative Examples 4 to 6 to be compared with Examples1 to 3, a glass plate for LCD with a size of 15×15 mm was sealed with anO-ring and then put into a tube furnace 40 of 650° C. (ComparativeExample 4), 700° C. (Comparative Example 5) and 750° C. (ComparativeExample 6), and SO₂ gas and O₂ gas were supplied thereto to make anenvironment of SO₂ 5%, O₂ 10%, similar to Examples 1 to 3. However, V₂O₅powder was not supplied, different from Examples 1 to 3, and moisture(H₂O) was supplied to the glass plate by using a bubbler. In addition,this state was maintained for the glass plate to react for 60 minutes.After the glass plates of Comparative Examples 4 to 6 were reacted for60 minutes in the tube furnace 40 of each condition, the tube furnace 40was cooled and all reaction gases were exhausted out of the tube furnace40 by using nitrogen gas.

After that, the IC analysis was performed to the glass plates ofComparative Examples 1 to 6, similar to Examples 1 to 3, and the numberof scratches was measured in the Taber manner. The analysis andmeasurement results are shown in Table 1 below.

TABLE 1 SO₂ O₂ Reaction Temp. IC analysis Number of (%) (%) time (min)(° C.) H₂O V₂O₅ (ppm) scratches Example 1 5 10 60 650 X Used 2.8 119Example 2 700 X Used 5.2 80 Example 3 750 X Used 8.7 80 Comparative 650X X 0.3 148 Example 1 Comparative 700 X X 0.6 130 Example 2 Comparative750 X X 1.1 138 Example 3 Comparative 650 Used X 0.9 134 Example 4Comparative 700 Used X 1.4 139 Example 5 Comparative 750 Used X 2.4 110Example 6

If the IC analysis results are considered in Table 1, in case ofExamples 1 to 3 using V₂O₅ as a SO₂ gas oxidation catalyst, the ICanalysis was measured as 2.8 to 8.7 ppm (5.6 ppm on average). However,in Comparative Examples 1 to 3 not using both H₂O and V₂O₅, the ICanalysis was measured as 0.3 to 1.1 ppm (0.7 ppm on average), and inComparative Examples 4 to 6 using H₂O and not using V₂O₅, the ICanalysis was measured as 0.9 to 2.4 ppm (1.6 ppm on average). From theseresults, it could be understood that CaSO₄ serving as a lubricant layeris formed much more on the surface of the glass plate in the case whereV₂O₅ serving as an oxidation catalyst is used together with SO₂ gas.

In addition, if the measurement results about the number of scratchesare considered in Table 1, in case of Examples 1 to 3, the number ofscratches occurring at the surface of a glass was 93 on average.However, in Comparative Examples 1 to 3, the number of scratches was138.7 on average, and in Comparative Examples 4 to 6, the number ofscratches was 127.7 on average. Therefore, it could be understood thatmuch more scratches occur at the surface of the glass plates accordingto the comparative examples. Particularly, in case of ComparativeExamples 4 to 6 using H₂O instead of V₂O₅, even though the number ofscratches is somewhat smaller than that of Comparative Examples 1 to 3not using both V₂O₅ and H₂O, but its effect is not so great incomparison to Examples 1 to 3.

When looking at the IC analysis results and the measurement results ofthe number of scratches using the Taber manner, it could be understoodthat, in a case where V₂O₅ serving as a SO₂ gas oxidation catalyst issupplied together with SO₂ gas, CaSO₄ serving as a lubricant layer maybe more sufficiently formed at the surface of the glass plate, and sothe scratch resistance at the surface of the glass plate may beremarkably improved. Therefore, the present disclosure may effectivelyreduce the formation of scratches at the surface of the glass plate.

Hereinafter, the improvement of the effect obtained by the formation ofa CaSO₄ layer according to the present disclosure will be examined inanother way. In other words, with respect to the glass plate of Example3 in Table 1 and the glass plates of Comparative Examples 3 and 6, theamount and thickness of a CaSO₄ layer formed at the surface of eachglass plate will be measured and compared.

Here, the amount of the CaSO₄ layer formed at the surface of each glassplate is obtained by measuring weight % of Ca and S by means of ESCA(EQC-0124). In addition, the thickness of the CaSO₄ layer formed at thesurface of each glass plate may be determined by etching the surface ofthe glass plate by means of Ar ion beam and judging the presence of S upto the depth of 50 nm. In addition, the measurement results are shown inFIGS. 6 and 7.

FIG. 6 is a graph showing measurement results of Ca and S contents ateach depth of the glass plate according to an example of the presentdisclosure and a comparative example, and FIG. 7 is a table whichexpresses the graph of FIG. 6 with numerals.

Referring to FIGS. 6 and 7, in case of the glass plate of Example 3according to the present disclosure, the S concentration at the surfacereached about 10 wt %, but in case of the glass plates of ComparativeExamples 3 and 6, the S concentration at the surface was just about 5 wt%. In addition, regarding the Ca concentration, in case of the glassplate of Example 3, the surface concentration reached about 7 wt %, butin case of the glass plates of Comparative Examples 3 and 6, the surfaceconcentration was just about 3-4 wt %.

Particularly, considering that, in case of Example 3, S was found up tothe depth of about 40 nm from the surface of the glass plate, the CaSO₄layer may be estimated as having a thickness of about 40 nm. However, incase of Comparative Example 3, S was found up to the depth of about 5 nmfrom the surface of the glass plate, and thus the CaSO₄ layer may beestimated as having a thickness of about 5 nm. In addition, in case ofComparative Example 6, S was found up to the depth of about 10 nm, andthus the CaSO₄ layer may be estimated as having a thickness of about 10nm. Therefore, it could be understood that the CaSO₄ layer formed at theglass plate of Example 3 according to the present disclosure is muchthicker than that of the glass plate of Comparative Examples 3 and 6.

Moreover, considering the depth up to about 5 nm from the surface of theglass plate, in case of the glass plate of Example 3, the Sconcentration was about 10 wt %, but in case of the glass plates ofComparative Examples 3 and 6, the S concentration was just about 3 wt %.

From the results, it could be understood that the CaSO₄ layer formed atthe surface of the glass plate according to the present disclosure ismuch thicker and richer.

Meanwhile, the method for manufacturing a glass as described above maybe performed by an apparatus for manufacturing a glass according to thepresent disclosure.

FIG. 8 is a block diagram schematically showing a functionalconfiguration of the apparatus for manufacturing a glass according to anembodiment of the present disclosure.

Referring to FIG. 8, the apparatus for manufacturing a glass accordingto the present disclosure includes a glass forming unit 100, a SO₂supply unit 200, an O₂ supply unit 300 and a catalyst supply unit 400.

The glass forming unit 100 forms a glass. In case of a float glass, theglass forming unit 100 may be configured to include a float bath.

The SO₂ supply unit 200 supplies SO₂ gas to the surface of a glassformed by the glass forming unit 100 such as a float bath. Preferably,in a case where a formed glass is introduced into an annealing furnace,the SO₂ supply unit 200 supplies SO₂ gas into the annealing furnace, sothat the SO₂ gas is supplied to the surface of the glass.

The O₂ supply unit 300 supplies O₂ gas to the glass formed by a floatbath or the like, so that an oxidation environment is formed around theglass. Therefore, the SO₂ gas supplied by the SO₂ supply unit 200 may beoxidized into SO₃ gas due to the oxidation environment.

Here, the O₂ supply unit 300 may supply pure O₂ gas and may also supplyanother gas together with the O₂ gas. For example, the O₂ supply unit300 may supply air to form an oxidation environment around the glass.

The catalyst supply unit 400 supplies a SO₂ gas oxidation catalyst withrespect to the SO₂ gas supplied to the glass. In other words, when theSO₂ gas is supplied to the glass by the SO₂ supply unit 200, thecatalyst supply unit 400 provides an oxidation catalyst for the SO₂ gasso that the SO₂ gas may be easily oxidized into SO₃ gas.

Preferably, the catalyst supply unit 400 may supply at least one ofV₂O₅, Fe₂O₃, CuO, TiO₂, Cr₂O₃, SiO₂, CaO, Al₂O₃ and WO₃ as the SO₂ gasoxidation catalyst.

At this time, the catalyst supply unit 400 may further supply at leastone of K₂O, K₂SO₄ and K₂S₂O₇ together with the SO₂ gas oxidationcatalyst.

The present disclosure has been described in detail. However, it shouldbe understood that the detailed description and specific examples, whileindicating preferred embodiments of the disclosure, are given by way ofillustration only, since various changes and modifications within thespirit and scope of the disclosure will become apparent to those skilledin the art from this detailed description.

What is claimed is:
 1. A method for manufacturing a glass, comprising:forming a glass; supplying SO₂ gas and a SO₂ gas oxidation catalyst tothe glass under an oxidation environment to form a lubricant layer atthe lower surface of the glass; and annealing the glass.
 2. The methodfor manufacturing a glass according to claim 1, wherein the SO₂ gas isoxidized into SO₃ gas under the oxidation environment.
 3. The method formanufacturing a glass according to claim 1, wherein the SO₂ gasoxidation catalyst includes at least one of V₂O₅, Fe₂O₃, CuO, TiO₂,Cr₂O₃, SiO₂, CaO, Al₂O₃ and WO₃.
 4. The method for manufacturing a glassaccording to claim 3, wherein the lubricant layer forming processfurther supplies at least one of K₂O, K₂SO₄ and K₂S₂O₇.
 5. The methodfor manufacturing a glass according to claim 1, wherein the annealingprocess is performed by using an annealing furnace, and the SO₂ gas andthe SO₂ gas oxidation catalyst are supplied in the annealing furnace. 6.The method for manufacturing a glass according to claim 1, wherein thelubricant layer forming process is performed in the range of ±100° C.from a transition temperature of the glass.
 7. A glass, manufactured bythe method for manufacturing a glass, defined in claim
 1. 8. A methodfor forming a lubricant layer on the surface of a glass by using SO₂gas, wherein the SO₂ gas is supplied to the glass together with a SO₂gas oxidation catalyst under an oxidation environment.
 9. The method forforming a lubricant layer on the surface of a glass according to claim8, wherein the SO₂ gas is oxidized into SO₃ gas under the oxidationenvironment.
 10. The method for forming a lubricant layer on the surfaceof a glass according to claim 8, wherein the SO₂ gas oxidation catalystincludes at least one of V₂O₅, Fe₂O₃, CuO, TiO₂, Cr₂O₃, SiO₂, CaO, Al₂O₃and WO₃.
 11. The method for forming a lubricant layer on the surface ofa glass according to claim 10, wherein at least one of K₂O, K₂SO₄ andK₂S₂O₇ is further supplied.
 12. The method for forming a lubricant layeron the surface of a glass according to claim 8, wherein the SO₂ gas andthe SO₂ gas oxidation catalyst are supplied in the range of ±100° C.from a transition temperature of the glass.
 13. An apparatus formanufacturing a glass, comprising: a glass forming unit for forming aglass; a SO₂ supply unit for supplying SO₂ gas to the formed glass; anO₂ supply unit for supplying O₂ gas to the formed glass; and a catalystsupply unit for supplying a SO₂ gas oxidation catalyst with respect tothe SO₂ gas supplied to the glass.
 14. The apparatus for manufacturing aglass according to claim 13, wherein the SO₂ gas oxidation catalystincludes at least one of V₂O₅, Fe₂O₃, CuO, TiO₂, Cr₂O₃, SiO₂, CaO, Al₂O₃and WO₃.
 15. The apparatus for manufacturing a glass according to claim14, wherein the catalyst supply unit further supplies at least one ofK₂O, K₂SO₄ and K₂S₂O₇.